Linux @lemmy.ml joejoe87577 @lemmy.world 11h ago

Backup solution for docker volumes

I'm trying to come up with a elegant way of backing up my docker volumes. I don't really care about my host and the data on the host, because everything I do happens inside my docker containers and the mapped volumes. Some containers use mapped paths, but some others use straight up docker volumes.

I've started writing a script that inspects the containers, reads all the mount paths and then spins up another container to tar all the mounted paths.

docker run --rm --volumes-from $container_name-v /data/backup:/backup busybox tar cvf /backup/$container_name.tar $paths

So far so good, this works and I can write all backups to my storage and later sync them to an offsite backup space.

But error handling, (nice)logging and notifications using ntfy in case of success / errors / problems is going to suck in a bash script. Local backup file rollover and log file rollover also just suck if I have to do all this by hand. I'm able to use other languages to write this backup util but I don't want to start this project if there already is a ready made solution.

So the question, is there a utility that can simply schedule arbitrary bits of script, write nicer logs for these script bits, do file rollovers and run another script on success / error?
All the backup programs that I can find are more focused on backing up directories, permissions and so on.

12 comments

Biggest issue I've encountered a couple times is some applications like Gitlab etc it's much better to use the backup process they provide than to try with disk copies etc. Although I haven't tried to use a btrfs send but rsync / cp / tar etc all seem to fail with the special files and extended fs attributes.
I made an ansible role for this:

https://github.com/CSUN-CCDC/ccdc-2024/tree/main/linux/ansible/roles/docker

It was designed for a cybersecurity competition, and can back up containers and volumes. The volume back up works by creating another container and then mounting the volume to that container, and within that container a simple tar backup is ran.
[Docker Volume Backup]((https://github.com/offen/docker-volume-backup )?
- That seems like the solution I was looking for. Google wasn't really helpful for me here :).
I just bind mount volumes I want to keep and use duplicati to backup the contents of my containers folder. Another idea if you are committed to docker volumes, is to also mount them to your backup solution.

I made my own solution since I wasn't impressed by projects I had found. There's two parts, the backup image and the restore image.

I use it like so:

services:
  restore_sabnzbd:
    image: untouchedwagons/simple-restore:1.0.5
    container_name: restore_sabnzbd
    restart: no
    environment:
      - BACKUP_APPEND_DIRECTORY=/docker/production/sabnzbd
      - BACKUP_BASE_NAME=sabnzbd
      - FORCE_OWNERSHIP=1000:1000
    volumes:
      - sabnzbd:/data
      - /mnt/tank/Media/Backups:/backups

  sabnzbd:
    image: ghcr.io/onedr0p/sabnzbd:4
    container_name: sabnzbd
    restart: unless-stopped
    user: 1000:1000
    volumes:
      - sabnzbd:/config
      - /mnt/tank/Media/Usenet:/mnt/data/Usenet
    depends_on:
      restore_sabnzbd:
        condition: service_completed_successfully
    networks:
      - traefik_default

  backup_sabnzbd:
    image: untouchedwagons/simple-backup:1.1.0
    container_name: backup_sabnzbd
    restart: unless-stopped
    environment:
      TZ: "America/Toronto"
      BACKUP_APPEND_DIRECTORY: "/docker/production/sabnzbd"
      BACKUP_BASE_NAME: "sabnzbd"
      BACKUP_RETENTION: "24"
      BACKUP_FREQUENCY: "0 0 * * *"
    volumes:
      - sabnzbd:/data:ro
      - /mnt/tank/Media/Backups:/backups
      
networks:
  traefik_default:
    external: true

volumes:
  sabnzbd:

The restore container looks for a file called RESTORED in /data and if one isn't found it'll try to restore the latest backup (if available) and then create a RESTORED file. The backup container ignores this file during backup.

As I'm not using a Swarm or cluster, I consider Docker volumes volatile and use mounts where I need persistence. All my configuration and other persistent data is under /opt/docker/<container>/<foldername>. And /opt/docker gets backed up regularly using restic.
./ bind mount everything in your compose file because dockers volume storage is bloody annoying to backup. Then you can just back up the one folder with everything in it.
- That's what I'm doing too. Kind of felt wrong to do that, but if you don't need the extra features of docker volumes this is the way. It always puzzles me when I read "Volumes are easier to back up or migrate than bind mounts." in the docs. How are these --volumes-from shenanigans easier than rsyncing some directory off the host?
This is a classic conundrum.

Containers and their volumes are supposed to be ephemeral (right?).

Yet we use them to run little apps where we configure settings etc in the app which we would like to “keep” - thus back up. Yes in a proper set up you would hook your container up to something that is not ephemeral like a database somewhere, but often we just want an app, see it’s got a self contained docker image, and just run it.

Whilst not in the spirit of things… I’ve tried using Borg backup however it just fails due to random permissions on the volumes.

I should spend more time looking into it but haven’t the time right now, could be the solution is specific to the app/container but the simplicity of just backing up a /volumes/* directory is soooo tempting…

Edit upon reflection, what about a sudo cron tab to zip volumes and set useful permissions on the zip. Then Borg to backup the zip. Borg (or at least vorta) can easily run scripts before/after and pass variables relating to the backup though.
- I can run the scripts by hand but I have to do everything else (logging, rollovers, notifications, etc.) by hand too, that is what I wanted to avoid.
  
  Permissions are not a big deal inside the containers and even If there is an issue, this is for my home nas. I don't really care If I have to spend a couple of hours to fix broken permissions after restoring something from a backup.
I don’t have an answer for this, but I wonder if something for this could be set up with a docker container. I know LinuxServer.io has a really good image system where you can run a container with “mods”. For example, you might be able to run their base Ubuntu / Fedora / Alpine image and then customizing it to run your script as a service / cron job / systemd service.

https://hub.docker.com/r/lsiobase/ubuntu

https://docs.linuxserver.io/general/container-customization/

12 comments